Facing ever tighter margins, one North Yorkshire dairy farmer concluded a DIY approach to diet feeder reform might be a cost effective solution. Howard Walsh reports.
Advised that worn auger flights on vertical auger diet mixers can impair mix quality and ultimately the efficiency of the dairy cow, a North Yorkshire farmer looked for a solution.
Not unusually for Nigel Dinsdale, who says he is not sure whether to describe himself as ‘an engineering farmer or a farming engineer’, it was a do-it-yourself solution.
With an engineering degree under his belt, he has designed, built and modified many a machine and installation for the family farming business, F. Dinsdale and Sons. Nigel and wife Suzie live at Manor Farm, Melmerby, Leyburn but partners in the family business include himself, father Colin, uncle Norman and cousin Peter.
But finding a reliable and cost-effective method of refurbishing worn auger flights on the 22cu.m Stoll twin-auger mixer did involve some head-scratching.
Mr Dinsdale says: “I had been to a meeting organised by Kite Consulting and it was there we were warned about the impact of worn augers on mix quality.
“Our own machine is a 2009 model and I must admit we had not really noticed any visible deterioration in mix quality. Nevertheless, with milk prices under pressure, no-one can afford to be losing yield, and at the same time, we have to look to save money where we can.
“The obvious options were replacing the machine itself – or the augers. My machine is already modified. It is raised by 300mm or so to suit the height of our feed barriers as I had not wanted to fit an elevator to the mixer. Coincidentally, the extra height effectively makes for a straighter driveline which is no bad thing. Anyway, it would have cost at least £1,000 to reconfigure a new machine because we have made other small changes to it as well.
“Two new augers would have cost around £3,500 each to replace, so I then looked at the possibility of retaining them but re-facing the flights,” says Mr Dinsdale.
“I came to the conclusion that Hardox steel, which is extremely durable, would be the best solution. It is not a very ductile material but by retaining the existing auger, and not fitting Hardox over the full width of the flights, and fitting it in segments, you do retain that necessary little bit of flexibility,” he says.
The new Hardox plates are simply bolted to the worn and much thinner existing flights.
“However, measuring up a series of 10mm plates – 16 per auger in fact on my machine – and creating a blueprint from which the steel company could make the plates was the hard bit. You have to replicate accurately the curve of the auger flight from top to bottom.
“What I did was make cardboard templates and then have all the dimensions drawn up on a computer, for these to be e-mailed to the steel company for plasma cutting and shaping.”
Mr Dinsdale wanted to make the actual job of fitting the plates, something which any competent farmer could do himself. Apart from repairing his own machine, he saw potential in being able to offer ready-to-fit plates for any vertical auger mixer.
By utilising the same M16 bolt holes which retain the auger knives to also bolt the Hardox plates, it meant the new plates only required an additional three holes to be drilled (M12) in the auger. Effectively, the trailing edge of one plate laps over and retains the leading edge of the next.
Bespoke engineering specialist, ‘Cad-n-Cut’ was charged with creating the cad drawings which, S M Thompson, Middlesboro, the steel company could follow.
“Because it is a very hard material, and not something you want to have to drill on-farm, the bolt holes have to be in precisely the right place,” says Cad-n-Cut’s James Hudson. “We just did one auger to begin with, then refined the design a little, and then refurbished the rear auger. Mr Dinsdale wanted to fit extra knives at the same time so we took that into account in drawing up the holes.
Precise design, cutting and fabrication of the new plates ensures the correct pitch and operation of the auger is maintained.
“We now have the templates on file for this particular model and will build up the portfolio as we refurb additional machines,” he says.
Mr Dinsdale says the cost of refurbishing with Hardox was approximately half the cost of new augers. Importantly however, there was a more or less immediate effect on milk yield.
“It was clear that what we had been told was true as our daily production went up by more than 200 litres with nothing else changed except the thoroughness of the mixing.
“Fitting the extra knives also made a big difference – not least in the time taken to mix the dry cow ration which has more straw in it. Mixing time was virtually halved and you can’t ignore that saving in diesel or the reduced wear on everything,” he says.
The new plates added approximately half as tonne to the weight of the mixer, but that simply entailed recalibrating the load cell weighing.
The Stoll normally mixes four loads for the cows each day and twice weekly for youngstock. Every three days it also makes a pre-mix – soya, rapemeal, distillers’ grains, barley, minerals, etc – ready for adding into the main mix.